brake light is on

[aggiedave98]

The brake light is on w/ my '89 suburban 1/2ton 2wd w/ disc in front and drum in the rear.

I rebuilt the rear brakes last weekend. My book seems to indicate the proportioning valve is bad, but I find it too coincidental. Is that the only thing that can set off the light??

[Longhorn Man]

Bad prop valve
Chafed wire shorted to ground
parking brake pedal being one click down
Prob valve needing reset.


To reset, get in the truck, and stomp on them like a mack truck cut you off when you're doing 100 MPH... panick stop sort of stomping.

[aggiedave98]

stomp on it w/ the key in the on position??

I think you mentioned getting an ajdustable valve in another post, right? where can you get one??

Oreily, Autozone, etc says just a normal one is a dealer part...

[Longhorn Man]

Key position doesn't matter.
Adjustable one can be purchaced at any high performance shop or mail order.
Jegs
summit

Are there any more out there any more?

[aggiedave98]

Ok, I'm confused now... my book calls it a combination valve. It has the 4 lines going out of it. But, at summit/jegs, there are proportioning valves but no combination valves. And, the proportioning valves just have 1 input/ 1 output. So, how do you hook it up?? And I guess I still need to buy a new combination valve if that's bad?? Confused!!

[aggiedave98]

Originally Posted by aggiedave98

Ok, I'm confused now... my book calls it a combination valve. It has the 4 lines going out of it. But, at summit/jegs, there are proportioning valves but no combination valves. And, the proportioning valves just have 1 input/ 1 output. So, how do you hook it up?? And I guess I still need to buy a new combination valve if that's bad?? Confused!!

any comments on this??

[piecesparts]

PULL your emergency brake pedal back off of the switch. The emergency brake cables are probably dragging a little and the switch on the E-brake is telling you that the pedal is not completely pulled back out. I have to get under my truck every now and then and put my foot on the cables and just give it a good push to get the pedal back to full out position. TRY IT...

[87burb]

My emerg. brake is tied up with a shoe string to the release...lmao po did that for whatever reason, but my brake light went on too after i was messing with fuses and installing the radio. Could that be my problem too? its one notch down?

[magnethead]

Originally Posted by 87burb

My emerg. brake is tied up with a shoe string to the release...lmao po did that for whatever reason, but my brake light went on too after i was messing with fuses and installing the radio. Could that be my problem too? its one notch down?

It doesn't matter how far down it is....if it's even just barely down, it'll trigger the switch

[piecesparts]

The brake light switch is on the E-brake mechanism and it is easy to knock out of position. Reach up under the dash and push the switch towards the metal piece that is supposed to depress it and the light may go out. My guess is that the PO figured out the switch problem and solved it with something really simple and absurd (a shoestring) sounds like my Geandmother was driving that truck.

[piecesparts]

Originally Posted by aggiedave98
Ok, I'm confused now... my book calls it a combination valve. It has the 4 lines going out of it. But, at summit/jegs, there are proportioning valves but no combination valves. And, the proportioning valves just have 1 input/ 1 output. So, how do you hook it up?? And I guess I still need to buy a new combination valve if that's bad?? Confused!!


So what are you trying to do? How do you know yours is bad? What I would do in this case is contact someone at one of the aftermarket brake companys (SSBC Stainless Steel Brake Company, Master Power Brakes, or MBM brakes, EVEN Early Classic Enterprises) for input. I am betting that they will tell you that a combination valve reads both Front and Back systems and sets up a proportioning difference and a trigger p[oint for a differential switch. Heck even Chevy Duty has this stuff.

[Longhorn Man]

A combination valve, or a distribution valve is way obsolete. That is 4 wheel drum talk.
The proportioning valve, whaich looks just like the combination valve, limits the amount of pressure goinfg to the rear brakes. The drums work off of much lower pressure than the disks do, plus, with the nose dive durring brakeing that unloads the rear, and the added weight over the nose from the engine, there is hardly any pressure going to the back in comparison to the rear.
To chevk your proportioning valve, to see if it is why your lite is on, unplug the little brown wire going to it. If the light goes off, then the proportioning valve is causing the light to come on.
Asuuming it has all been bled properly... and you tried resetting it with the stomp method, and there are no kinks in any of the lines down stream from the valve, and the master cylinder is new... then the valve is probably faulty.

[aggiedave98]

Well, after work, I checked the brake pedal and that was fine. It was hitting the stopped and I could see the switch turning on when I pressed down a few clicks.

So then I just saw Longhorn's post and went out there and disconnected the wire. LIGHT OFF!!

BUT, more importantly, you said one word... "bled" that was the key... I replaced the rears but nobody was around to help and I forgot to bleed them!!!! That's probably it, don't you think??

So thanks guys, especially Longhorn! (once again).


Now, the question is how do you guys bleed your brakes w/ one person? I have a mityvac but that doesn't seem to work well. I usually use the 2nd person, but too often I don't have one around...


Longhorn, the other thing though is my factory manual calls it a combination valve. It talks about a height sensing proportioning valve on some models.

Also, this talks about a combination valve:

You will find a combination valve on most cars with front disc brakes and rear drum brakes.

http://auto.howstuffworks.com/master-brake2.htm

and:

The valve does the job of three separate devices:

The metering valve
The pressure differential switch
The proportioning valve

which my factory manual also says.

[Bad Karma]

Here is a pic I found somewhere online when I was researching this subject for my rear discs (which are coming off this weekend! )

The one on top is the one on my '77 Sub. It has a pin in the end (under the rubber boot) that must be held in when power bleeding the brakes, from what I have read. Just pumping the pedal and cracking the bleeders *shouldn't* cause it to pop out... On the other type, the pin must be pulled out, I believe, not 100% sure on that.

[James McClure]

Originally Posted by aggiedave98

Well, after work, I checked the brake pedal and that was fine. It was hitting the stopped and I could see the switch turning on when I pressed down a few clicks.

So then I just saw Longhorn's post and went out there and disconnected the wire. LIGHT OFF!!

BUT, more importantly, you said one word... "bled" that was the key... I replaced the rears but nobody was around to help and I forgot to bleed them!!!! That's probably it, don't you think??

So thanks guys, especially Longhorn! (once again).


Now, the question is how do you guys bleed your brakes w/ one person? I have a mityvac but that doesn't seem to work well. I usually use the 2nd person, but too often I don't have one around...


Longhorn, the other thing though is my factory manual calls it a combination valve. It talks about a height sensing proportioning valve on some models.

Also, this talks about a combination valve:

You will find a combination valve on most cars with front disc brakes and rear drum brakes.

http://auto.howstuffworks.com/master-brake2.htm

and:

The valve does the job of three separate devices:

The metering valve
The pressure differential switch
The proportioning valve

which my factory manual also says.

Anggiedave: Bleeding brakes with 1 person. Problem with mighty vac is it works to well & sucks air past the bleeder screw. I have had mixed results with gravity bleeding, EG, fill the master cylinder and open all 4 bleeders and wait for fluid to pee out and hope all the air is out. Second method is the "coke bottle" method. Take a clear bottle and fill it half full of brake fluid. Put a hose on the bleeder after you open it, put the hose into the bottle all the way to the bottom, fill master and start pumping brake pedal. Fluid in bottle prevents air from getting back in when you release pedal and bottle collects fluid as you pump. Give the pedal 5 or 6 strokes and check master cyl. Start at L/rear wheel, then R/rear, then R/front, then L/front. I built a pressure bleeder because I work alone and come up against this problem pretty often. Jim

[aggiedave98]

why are the discs coming off?? if you put on discs, do you have to get a new valve (whatever kind we're going to call it)?

[Bad Karma]

I switching back to drums because the discs are just a pain. They seem to warp easily, and after doing a little research, the rotors are custom machined/drilled Corvette rotors, not something I can just run to parts store and pick up...

Plus, I am not happy with the kit, the pads hang over the top of the rotor, which causes problems as they wear. Live and learn, I guess. I'm not interested in trying another brake kit, so I'm just gonna put it back to stock.

I did change the combination valve to a disc/disc unit when I swapped, and I bought a new AC Delco disc/drum valve for when I swap back (I pitched the original in the trash, thinking I would never need it again).

[piecesparts]

So I guess, we should ask: What system did you install on the truck? Was it a front and rear disc setup? This way, we could not make the same errors.

[Bad Karma]

If you search my user name and look for threads about rear discs, you may find the information you seek....

[James McClure]

Dave, glad you like the "coke bottle" trick, now the $64 question, did you get it fixed, did the light go out?

[aggiedave98]

James,

I honestly can't remember what happened. It was 14 months ago and I sold it last November. I know the light did go out but I don't remember why.

It's killling me that I can't remember!!!

[James McClure]

Aggie: Don't you just hate that? I don't know how old you are but I'm older than dirt or white dog crap, whichever you choose and I have C.R.S. real REAL bad. Can't Remember S**t. I'm almost 60 BTW. Jim

[slugish]

James,

Just turned 61 today , dont feel like the lone ranger on the forum.

By the way was having same problem with my 84 / used the stomping method to get my brake light to go off . Recently rebuilt rear drum brakes with new drums . Still have hard pedal & a little spongy & have to steer it when Ihit the brakes a little hard ( pulls to one side pretty hard) which it did befoer I rebuilt them . I just replaced cylinders & drums, springs seemed ok.
Any ideas of what to check for this problem.

By the way again , I know about white dod crap but what is C R S ? WHAT ARE THE SYMPTOMS?

[marvxyz1]

If you have a recurring problem of your wheels pulling to right or left, when you hit your brakes, it may be caused by a defective rubber brake hose up front. There is no way to check these rubber hoses ..only replace.

[slugish]

thanks for the info. probably should replace with stainless flex hose do you think ?